Guard for machinery.



B." W. PINKERTON.

GUARD FOR MACHINERY.

APPLICATION FILED APR. I 1911.

999 464 Patented Aug. 1, 1911.

' eoaaca.

urn earns arr FFTQ .ERVIN W. PINKERTON, OF ROCHESTER, NEW YQRK.

GUARD ron MACHINERY.

Specification of Letters Patent.

Paton-ted Aug. 1, 1911.

Application filed April 1, 1911. Serial No. $18,485.

new and useful Improvements in Guards for lllachinery, of which thefollowing is a specification.

This invention relatesto a guard adapted to prevent injury to the handof an operator in feeding material to the operative instrumentalities ofa machine.

' In machines of certain types, particularly in a die-press, it isimpracticable to provide guards by which the operator can be abso-Jfitely prevented from accidentally inserting the hand between the dies,or other operative instrument-alities, when the machine is running,since guards for this purpose would interfere with the properpresentation of the bers which interfere in any way with the convenientoperationof the machine. this end I propose to employ an electriccurrent in such'a manner that, in case the operator allows his hand toapproach into dangerous proximity with the operative instrumentalities',the hand is subjected to a shock. This shock not only gives the operatorunmistakable warning of danger, but it is also possible, by the use of acurrent of a power- 111, but not dangerous, character, to cause aninvoluntary movement of the hand by which it is immediately andinevitably with drawn out of danger.

It has been previously proposed to employ electricity to guard atpunching-press in the manner stated, by means of apparatus which isautomatically thrown into operation when the dies of the punching-pressmove together. and which is thrown out of operation again automaticallywhen the dies move apart. Such a construction is effective,

however, only in machines provided withoperative instrumentalitieswhich, like dies,

moveintermittently toward and from each other. In the present invention,however, I arrange the electrical apparatus tobe thrown into, and outof, operation by the treadle, or other manually-operable device bpvhichthe machine as a whole is thrown into or out of operation.Accordingly, my novel arrangement. is applicable to machines of allkinds having dangerous operative instrumentalities, whether theseoperate intermittently, as in a press, or constantly, as in the case ofa sawing or molding-machine, or the like, the electric apparatus beingoperative so long as the operator retains the t'readle in depressedposition to continue the operation of the machine.

A. further feature of the invention consists in the use of the treadle,or other manually-operable device, as one electrode for conducting thecurrent to the body of the operator, whereby I simplify the construction of the device and avoid the necessity of an independent electrodefor the purpose.

- The accompanyingdrawing is a side-elevation'of a die-press providedwith a guard embodying the present invention.

The machine of the drawing is a die-press of ordinary form, having theusual upper and lower dies 1 and 2. The lower die rests upon a metalplate or bed 3-supported on the frame of the machine, and this plateserves as a conductor for the electric current. The front-portion of theframe of the machine is covered by insulating material 4,50 that theoperator may touch this partwithout receiving a shock, butif, in feedingthe material between the dies, he inadvertently permits his hand toapproach into dangerous proximity to the dies, the contact between hishand and the plate 3 subjects the hand to a powerful shock, causing thehand to be immediately and involuntarily withdrawn.

To complete the electric circuit through the operator I make use of thetreadle 5 of the machine as an electric contact in such circuit. Thistreadle is insluated'from the pivoted arm 11 on which it is supported,and is connected with one terminal of the source of electricity. Thesource of electricity maybe an ordinary induction-coil 6.

- of which the primary, winding is connected tor depresses the treadle 5to start the machine in the usual manner, the arm 11 draws down the rod10, thus throwing the clutchmechanism into operation and at the samemachine, the switch 9 breaks the primary circuit of the coil, and thereis no further consumption of current.

My invention is applicable to machines of various types, and obviouslyvarious sources of electric current may be employed. Where the machineis not provided with any member conveniently located to serve as acontact to engage the hand of the operator it will be obvious that aspecial part may be applied to the machine for this purpose.

1. In combination with a machine having operative instrumentalities anddriving mechanism therefor, including a normally inoperative clutch,means for generating high-tension electricity, a conductor locatedadjacentsaid instrumentalities and in the path of movementof theoperators hand when feeding work to the machine. a man ually-operablemember for throwing and holding said clutch into operation, connectionsbetween said generating-means, said conductor and said manually-operablemember, whereby a circuit may be produced 2. In combination with amachine having 4.5

operative instrumentalities and a treadlecontrolled driving mechanismtherefor, means for generating high-tension electricity adapted toproduce a powerful, but not dangerous, shock, a conductor locatedadjacent said instrumentalities and in the path of movement of theoperators hand when feeding work. to the machine, and connectionsbetween said generating-means, said conductor and the treadle of themachine, whereby 'a circuit may be produced through the operators bodyin case the hand is brought into contact with said conductor.

3. In combination with a machine having operative instrumentalities anda treadlecontrolled drivingmechanism therefor, means for generatinghigh-tension electricity adapted to produce a powerful, but notdangerous, shock, a conductor located ad-- jacent said instrumentalitiesand in the pat of movement of the operators hand when feeding work tothe machine, connections between said generating-means, said conductorand the treadle of the machine, whereby a circuit may be producedthrough the operators body in case the hand is brought into contact withsaid conductor, and a circuit-breaker operated by the treadle andconnected with said generatingmeans to throw the latter into operationwhen the treadle is depressed to start the machine.

ERVIN IV. PINKERTON. Witnesses:

D. Gmuvnn, C. W. CARROLL.

Copies of this patent may be obtained for five centseach, by addressingthe Commissioner of Patents, Washington, D..C.

